IISC team designs 'salt' to combat bacterial infections

While a combination of antibacterial and antimicrobial medications are used to treat infections, these can differ in their properties, some of which may not have the desired result. A physical mixture of the two drugs may not be very effective, said experts. A team from the Indian Institute of Science (IISc), Bengaluru, have addressed this problem by designing a solid in the form of a salt, which is a combination of two known drugs.Mihika Basu | Bangalore Mirror Bureau | November 01, 2016, 13:30 IST

While a combination of antibacterial and antimicrobial medications are used to treat infections, these can differ in their properties, some of which may not have the desired result. A physical mixture of the two drugs may not be very effective, said experts. A team from the Indian Institute of Science (IISc), Bengaluru, have addressed this problem by designing a solid in the form of a salt, which is a combination of two known drugs.

Prof Gautam R Desiraju, a structural chemist at the solid state and structural chemistry unit of IISc, told Bangalore Mirror that laboratory tests have revealed that this ‘salt’ launches a quicker and stronger attack against many bacterial infections, as compared to the parent drugs. It is also a safer and more beneficial therapeutic treatment as indicated by all laboratory tests, says the research team. Even if a smaller amount of the salt is prescribed, the amount of drug entering the bacterial cells will be more than the usual dose, they added.

“Bacteria are the cause of some of the most deadly and widespread diseases in human civilisation. Bacterial infections, with complications of drug resistance from increased antibiotic use, have increased dramatically in recent years. Escherichia coli and Staphylococcus aureus are two of the most notorious bacteria that affect several body tissues and cause a variety of diseases such as complex urinary tract infection and respiratory and skin infections,” said an official release from ‘Research Matters’

“Combinations of antibacterial and antimicrobial medications are generally used to treat these infections. Most of the marketed drugs are in the form of physical mixtures with their own flaws: the two medicines are different in their chemical and physical properties, resulting in different efficacies. IISc scientist Prof Desiraju, and post-docs Somnath Ganguly and Shanmukha Prasad Gopi have offered a balanced approach to tackle this problem by designing a new multicomponent solid, which is a combination of the antibacterial norfloxacin and the antimicrobial sulfathiazole in the form of a salt,” it added.

Solubility and permeability are two desirable properties in a drug. The researchers said that generally, most of the oral drugs are usually absorbed into the bloodstream in the small intestine. Once these drugs are absorbed by the blood and transported to the target areas, they try to enter those cells that need to be acted on, the release said.

However, according to Prof Desiraju, the problem with a physical mixture of norfloxacin and sulfathiazole is that norfloxacin is only slightly soluble and not at all permeable. This can make the medication less effective. But, in the new salt form, these drugs are found to diffuse faster and together. The team further said that these improved characteristics increase the ease with which the anti-bacterials enter bacteria. Once inside, they prevent the microbes from multiplying, thus restricting their numbers. With their population kept to a minimum, the body’s immune system is able to effectively fight and eliminate them, as per ‘Research Matters’.

“Not all anti-bacterials are effective against all kinds of bacteria because of the differences in the bacterial targets. If the dosage of the medications is not strong enough, they can be overpowered by the bacteria causing a recurrence of the infection and development of resistance. Both individual drugs are well-known drugs. But when we put them in combination, we are getting more properties. Sulfathiazole is able to “drag” norfloxacin through the cell membrane, which it won’t do by itself. Thus, we are getting a combination drug with better properties. This is important for countries like India where we are strong on the generic pharma side. We can take existing drugs and get extra IP protection out of them by modifying the solid state properties. It is a kind of molecular-level formulation,” said Prof Desiraju.

The team has applied for patent and subsequently published its findings in the ACS journal Molecular Pharmaceutics. The researchers, who have been working on this project for a couple of years now, now plan to look for a company to licence the patent, to take the project forward.